A driver covers 120 miles at 60 miles per hour, then another 120 miles at 40 miles per hour. What is the average speed for the whole trip?

Correct answer to question 12 (Arithmetic Reasoning): 48 miles per hour

Method

Average speed is total distance divided by total time, not the average of the two speeds. The legs take 2 hours and 3 hours, so 240 miles over 5 hours gives 48 miles per hour. Averaging 60 and 40 to get 50 is the common trap, because more time is spent at the slower speed.